Originally Posted By: Speak2Mountain
THEORETICALLY Speaking: Would a higher flow air filter (K&N/S&B) do more to prevent running rich than a lower flow/higher capture filter?
Theoretically speaking.....
Theoretically speaking, no. Neither air filter is designed to "prevent running rich" .
Even a carbed engine is built and tuned to deliver the correct mixture with whatever restriction the OEM filter applies, so IF there was an effect at all, the higher flow filter would run lean, rather than the OEM filter running rich.
Practically speaking, even on a carbed engine, there is negligable effect until the filter is heavily clagged, at least according to the most readily available study.
https://www.fueleconomy.gov/feg/pdfs/Air_Filter_Effects_02_26_2009.pdf
Originally Posted By: MichiganMadMan
As previously stated: With a carburetor air filter restriction matters.
As previously stated, no it doesn't.
At least not according to the above study. (I think they only tested one carbed car).
Severe air filter clogging matters, although to get more than a 2% drop in fuel economy they had to add so many shop towels that drivability was severely impacted and the filter parially collapsed.
Designed air filter restriction has negligable effect.
Recently I rigged a water manometer as a restriction gauge and decoker. The filter has been on the car since I bought it (about 7 years IIRC) in dusty Taiwan and the restriction was not measurable. I had to add paper towel and toilet paper to the filter to get the gauge/decoker to work.